The invention relates to a gear shift device for a manual gear change transmission.
Such a gear shift device is the subject of the German Patent publication 198 03 608. It is aimed at the requirements of a remote-control gear shift device.
In a direct shift device of gear change transmissions, shift rails, which are used in a generally known way for changing the gears, are arranged next to one another in the transmission housing. A shift lever with a shift finger engaging alternately shift slots of the shift rails arranged in a row next to one another is mounted in a bearing part of the manual shift lever and is positively guided by the bearing part.
In a plurality of manual transmission with a direct gear shift device, the manual shift lever is supported by a spherical bearing structure disposed in a shift dome, which is arranged on the transmission case. The manual shift lever has an extension with a shift finger, which engages alternately the shift slots. It is assumed, in this arrangement, that the shift ratio and is the selected shift ratio. That is to say, the ratio of the distance between operating knob of the shift lever and the bearing sphere center to the distance between the bearing sphere center and shift finger actuation center is identical both for the shift plane and for the selection plane.
Often, however, ergonomic requirements lead to different transfer ratios, which can be achieved only via a cardanic support structure wherein the pivot axes for the shifting movement and those for the selecting movement are arranged one above the other and rotationally displaced by 90xc2x0 relative to one another.
Because the shift forces are generally quite high the shift ratio is set very high in order to make the shifting comfortable. This however requires that the bearing center point is disposed low in the shift dome. On the other hand, the shift selection gates should be disposed close to one another. This again results in a lower selection side ratio with the bearing center point disposed high in the shift dome, and therefore to an often very high shift dome, which is often undesirable.
It is the object of the present invention to provide a direct shift device with a low shift dome and with a low selection side ratio.
In a gear shift device for a manual gear change transmission with a plurality of shift rails disposed in the transmission housing and a shift lever pivotally mounted on a joint carrier supported on a shift dome above the shift rails, the shift lever has a forked downwardly extending end in which a shift finger is received and pivotably supported by the joint carrier so as to project from the shift lever downwardly into engagement grooves of the shift rails and the shift finger is snugly engaged by the lower forked lever end of the shift lever for pivoting the shift finger at a rate which is increased with respect to that of the lower shift lever end.